Electron transport and magnetic properties of semimetallic LuAs

Polycrystalline samples of LuAs with a residual resistivity ratio (RRR) between 2.52 and 3.38 were examined by: X-ray diffraction, magnetisation, resistivity, magnetoresistivity, Hall coefficient and thermoelectric power S(T), in addition to the nuclear magnetic resonance (NMR) of As-75 and Lu-175 nuclei. The density and mobility of carriers for the valence and conduction bands were determined for the RRR = 2.52 sample and used for the calculation of thermoelectric power, S-c(T). The value of S-c(T) fits well with that determined by experiment. The sample shows a charge imbalance with the number of electrons n, (holes, p) equal to 1.52 x 10(20) (1.12 x 10(20)) e/cm(3) at 4 K. This imbalance decreases with temperature, reversing after passing a minimum at similar to 80 K and then increasing to n (p) = 9.4 x 10(19) (1.42 x 10(20)) e/cm(3) at 300 K. The As-75 NMR Knight shift is found to be temperature independent and equal to 0.102% and the Lu-175 NMR resonance frequency is shifted to higher values by ca. 0.011% with respect to that of LuSb. All data indicate that LuAs belongs to semimetals and the clearly observed Lu-175 NMR multiquadrupolar echoes suggest the existence of defects in the cubic structure of the investigated samples. (C) 2013 Elsevier B. V. All rights reserved.